Grinding or disintegrating cement or other materials.



. A. SMALLWOOD.

GRINDING 0R DISlNTEGRATlNG CEMENT OR OTHER MATERIALS. APPLICATION FILEDAPR-18.1916.

Patented Apr. 9,1918.

ALFRED SMALLWOOD, OF LONDON, ENGLAND.

GRINDING OR DISINTEGRATING CEMENT OR OTHER MATERIALS.

Specification of Letters Patent.

Patented Apr. 9, 1918.

Application filed April 18, 1916. Serial No. 91,941.

To all whom it may concern.

Be it known that I, ALFRED SMALLWOOD, a subject of the Kingdom of GreatBritain, residing at 42 Hargrave Park, Highgate, London, N in the countyof Middlesex, England, have invented certain new and useful Improvementsin or Relating to the Means for Grinding or Disintegrating- Cement orother Materials, of which the following is a specification.

This invention comprises certain improvements in or relating to themeans for grinding or disintegrating cement or other material, and itrefers more particularly to the type of device, a number of which areused in connection with a tube mill, the said clevices being in thenature of short cylindrical or like members which are placed within thetubular chamber in company with the material to be ground, in such amanner that the cylindrical or like members roll in relation to the wallof the chamber, and in relation to each other, thereby grinding orcrushing the material. In the present invention I employ cylindrical orlike devices of a hollow character, and these are furnished with arecess or opening extending from end to end, but according to thepresent invention the external surface of the device is casehardened,the inner or main structure of the device being allowed to remain of aspringy or like character adapted to permit of temporary contraction. Bythis process a suit ably hard grinding surface is obtained externally,while the inner part of the metal is enabled to give in the event of anexcessive stress, which might otherwise result in breakage.

In order that this invention may be clearly understood and readilycarried into practice, reference may be had to the appended explanatorysheet of drawings wherein Figure 1 is an end elevation of a grinding orcrushing device, according to the present invention, and Fig. 2 is aside view thereof.

In a convenient embodiment of the present invention, the grindingdevicesa are each comprised of a tubular member, which latter is furnishedthroughout its entire axial length with a longitudinal slit saw cut, oropening 6, which latter is incorporated in such a manner as to leave adistinct space or gap which is enabled to partially or entirely close inthe event of the device being subjected to an excessive stress.

The device may be composed of metal of a springy or resilient character,whereby after being temporarily subjected to this stress, the device isenabled to recover its original form, the device being thus of aresilient or springy character adapted normally to fulfil its functionof grinding the material but furthermore adapted to give to a sufficientextent in the event of an excessive stress, which might otherwise resultin fracture.

F or the purpose of providing a suitable grinding surface, the externalsurface of the grinding device is case-hardened, but- I effect thecase-hardening process in such a manner that only the outer portion ofthe metal is case-hardened, the inner portion being allowed to remain ofa character whereby the springy, tenacious, fibrous, or other qualitiesdesired to permit of contraction in the event of an excessive stress arepreserved.

In order to carry out the case-hardening process in connection with onlythe external portion or layer of the metal, I fill the tube internallywith a suitable filling or insulating material, such as clay, prior tothe casehardening process, after which the devices thus prepared aresubjected to the casehardening process in the presence of appropriatecase-hardening composition, with the result that the latter is unable toaffect any part of the metal, except the external surface, in connectionwith which the process of case-hardening is desired.

After the case-hardening process has been effected, the filling may beremoved, and a device is produced having a suitable grinding surface andpossessing furthermore the quality enabling it to appropriately give inthe presence of an excessive stress, thus satisfactorily avoidingfracture.

What I claim as my invention, and desire to secure by Letters Patent isA grinding element for a ball mill, consisting of a cylindrical shellhaving an opening in the Wall thereof on one side only, and extendingfrom end to end thereof.

In witness whereof I have hereunto set my hand in the presence of twowitnesses.

ALFRED SMALLWOOD.

Witnesses ARTHUR BROWN, HoLLIs BROWN.

copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

